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Setting aside a highly radioactive material until the radioactivity has diminished to a desired level.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a decrease in body temperature in warm-blooded animals and humans as a result of heat emission that exceeds the formation of heat in the organism. Such a decrease may also result from derangement of the thermoregulatory mechanisms. Cooling is also called hypothermia.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

datacenter cooling

Maintaining the datacenter at an efficient temperature. Datacenter cooling not only involves the deployment and maintenance of air conditioning, but in order to provide the most cooling per square foot, the most efficient server configurations must be employed. For example, rack servers are more efficient than stand-alone servers, and blade servers are more efficient than rack servers. The type of heat sinks and CPU coolers used in each server are also a factor. See KyotoCooling.

Local Smart Cooling
Smart cooling is a type of datacenter cooling that monitors specific areas within the facility and adjusts the temperature locally rather than the entire room. Dynamic Smart Cooling (DSC) was an earlier HP solution for smart cooling.

Develop a Heat Map
A definitive way to determine the airflow in a room is to generate a heat map. The analysis of heat flow can be used to locate air leaks and determine how to relocate equipment for greater airflow.


A device that uses motor-driven blades to circulate the air in a computer or other electronic system. Today's CPUs run extremely hot, and large computer cabinets use two and three fans to reduce temperature. See FanCard.

heat pipe

A tubular device that is very efficient in transferring heat. Using a metal container (aluminum, copper, etc.) that holds a liquid (water, acetone, etc.) under pressure, the inner surface of the tube is lined with a porous material that acts as a wick. When heat is applied to the outer area of the tube, the liquid inside the tube boils and vaporizes into a gas that moves through the tube seeking a cooler location where it condenses. Using capillary action, the wick transports the condensed liquid back to the evaporation area. See heat sink.

How It Works
A variety of liquids and wicks are used to make a heat pipe, but the principle is the same. The liquid evaporates into a gas that travels to the cooler end of the pipe, condenses back into liquid and returns via the wick.

A CPU Cooler
In this high-end TNN500A computer cabinet from Zalman (, the heat pipe transfers the heat from the CPU to the wall of the case, which acts as a giant heat sink. This combination of heat pipe and case eliminates the need for a noisy fan.

heat sink

A material that absorbs heat. Typically made of aluminum, heat sinks are widely used in amplifiers and other electronic devices that build up heat. Small heat sinks are the most economical method for cooling microprocessors and other chips. They are commonly found glued or clipped to the top or the side of the chip package. See heat pipe, CPU cooler and thermal grease.

Heat Sink on a Chip
This type of heat sink is glued to the top of the chip, typically a CPU chip, which generates considerable heat.


A water-free datacenter cooling system from KyotoCooling ( that uses a rotating heat exchanger wheel that resides above the equipment floor. The rising hot air from the servers is absorbed in the wheel, which is cooled with outside air. The cooler air is sent back down to the servers.

Commonly used in combination with traditional air conditioning (DX compressors), which can be idle as much as 75% of the year depending on geographic location, KyotoCooling saves water and power. In addition, KyotoCooling datacenters can have equipment on cement floors rather than raised floors, allowing taller, heavier equipment racks to occupy the same footprint. See rack mounted and datacenter cooling.

The KyotoCooling System
A massive, spinning corrugated aluminum wheel (the KyotoWheel) is cooled with outside air in one plenum while it absorbs the heat from the server racks in another.

water cooled

A cooling system that uses water. Like a car, water cooling systems for electronics circulate water in a loop between the heat sources and a cooling radiator. In personal computers, the components that generate the most heat are the CPU chip and GPU (graphics processor chip). Every second, trillions and quadrillions of transistor state changes take place, which generate substantial heat. See CPU, GPU and active area.

Faster and Quieter
Water cooling systems appeal to people who push the envelope and build personal computers with the fastest chips, because water cooling is very efficient. They also eliminate large, noisy fans. Water cooling is not new. Some early computers and large mainframes were water cooled, but gave way to air cooling as advancing chip technology reduced their overall size. Water cooling a room-sized computer required extensive plumbing.

A Closed Water Loop
The Zalman Reserator radiates the heat from the hot chips to the outside world, and only a small fan is required. Water is pumped from the radiator to the CPU to the GPU to a flow indicator (in front of case) and back to the radiator.

A Closed Water Loop
The Zalman Reserator radiates the heat from the hot chips to the outside world, and only a small fan is required. Water is pumped from the radiator to the CPU to the GPU to a flow indicator (in front of case) and back to the radiator.

Built Into the GPU Card
This PNY graphics card cools itself and the CPU. The radiator and fan (left) cool the water from the card, and the center unit is placed over the CPU. (Image courtesy of PNY Technologies,
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